Generally, feeders for flowing streams of molten glass have been made from precious metals and alloys of precious metals. Recently, specially processed laminates of refractory metals sheathed in precious metals have been developed and utilized in fabricating such feeders. For example, see U.S. Pat. No. 4,342,577; 4,402,718; 4,404,009 and 4,441,904.
In addition to high temperature, oxidizing environments, various sections of the feeders encounter other types of demanding situations.
For example, the ear or terminal, which projects outwardly from the body of the feeder or bushing and is adapted to receive electrical power from power supply lines clamped or bolted thereto, generally receives combined normal and sheer stresses due to the weight of the electrical connections attached thereto. Further, the ears or terminals are even more stressed as the connections are being bolted to the terminals due to the torque applied to the fasteners.
In some instances, such additionl stresses may tend to delaminate the refractory metal core from its precious metal frame along the edge thereof.
The present invention provides for a mechanical interlocking or interengagement between the refractory metal and the precious metal at highly stressed regions.